This invention relates to a recording card for displaying updatable magnetic information as a visible image. More particularly, the invention relates to a visible image magnetic card comprising a magnetic recording sheet, a display sheet, and a display cell which is sandwiched therebetween, with magnetic particles confined within the display cell. In this magnetic card, a magnetic latent image is formed in the area of the magnetic recording sheet which corresponds to the display cell and the magnetic particles are transported through the display cell such that they form a visible image in a pattern related to the latent image.
A magnetic card can, in general, be fabricated using comparatively inexpensive and highly reliable components in the record/reproduce system. In addition, the magnetic card has a comparatively large recording capacity, permits instantaneous recording, reproduction and erasure, can be reused. This offers convenience in carrying and handling, and the device may be manufactured at low cost. Because of these many advantages, the magnetic card is currently used for cash cards, credit cards, train ticket credit cards and other media for transferring information to and from automatic dispensing machines and office-automation equipment.
One problem with known magnetic cards is that the information recorded thereon is invisible. Separate printers, typically impact types are used to separately provide a visual image. A need therefore exists to develop a magnetic card that presents a desired part of the recorded information as a visible image in the form of letters or numbers and does not require separate printers.
In order to meet this need, the inventors have proposed a visible image magnetic card which consisted of a magnetic recording sheet, a transparent sheet, and a display cell sandwiched therebetween in which magnetic particles were confined in such a manner that they could migrate from one location to another. Such is disclosed in Japanese Patent Publication No. 852/1981. When a magnetic latent image is formed in the area of the magnetic recording sheet which corresponds to the display cell by magnetizing said area with a multi-track (e.g 7-track) head, the magnetic particles in the display cell are attracted to the image area, producing a visible contrast with the unmagnetized non-image area. The visible image may be updated by erasing it and then writing a new magnetic latent image. One problem with this technique is that the image is not sharp.